Issue Three 2012 - Issue #17

Gastro CSI

Story by James Hutson

Each year in Australia
there are more than 5.4 million cases of gastro, involving 15,000
hospitalisations and 80 deaths. The burden on the healthcare system is over
$1.2 billion per annum, with additional costs arising from loss in lifestyle
and productivity.

Gastrointestinal illnesses are generally caused
by three types of bacteria: E. coli, salmonella and campylobacter jejuni. The
general public tends to be more familiar with salmonella outbreaks, but Louise
Dunn, investigator and program manager for Swinburne’s Bachelor of Health
Science degree, notes that campylobacter jejuni is the most significant cause
of food-borne illness in Australia and worldwide.

“We have about 6000 cases per year being
reported in Victoria.
It is a significant burden. The incidence of
infection also appears to be
increasing across all age groups, including
children and young adults.”

Difficult
to detect

A big problem with identifying and controlling
campylobacter jejuni is that most of the infections seem to be sporadic. It
might be from contaminated water or contact with pets, birds, animals or food
(such as chicken, offal or undercooked meat).

“Outbreaks aren’t always occurring in a
particular pattern or interval, they are just an occurrence, and each year only
one or two outbreaks are detected,” says Dunn. “This means that there is not
enough information about how to manage and detect the source of the infection.”

Current testing methods are time consuming and
require skilled personnel. The current “gold standard” uses gel electrophoresis
to genetically differentiate the specific strain (genotyping). Growing cultures
of the sample for genotyping analysis takes three to four days, a delay that
makes tracing the origin of the contamination through accurate interviews and
further sample collecting more difficult.

Finding
the source

Tracing the origin or source of the
contamination is critical if health outcomes are to improve. The Victorian
Department of Health is looking for ways in which they can use evidence for
better decision-making. To this end they have awarded a research scholarship to
Swinburne PhD student Monir Ahmed to focus on more rapid ways to detect
campylobacter jejuni and better inform the Victorian Department of Health’s
policies.

“Swinburne has a long-term relationship with the
Victorian Department of Health,” says Dunn. “We produce a lot of graduates who
work in regulatory and surveillance areas within local and state government departments
and this scholarship allows us to investigate how we can help the food safety
system by developing techniques for detecting outbreaks of campylobacter jejuni
more readily.”

Instead of relying on genotyping, Ahmed has
obtained samples from the University of Melbourne’s Microbiological Diagnostic
Unit and is working to identify a selection of virulent (toxin) genes
associated with the campylobacter infection. These gene groupings could then be
used to more quickly and accurately identify and categorise different strains.

Ahmed uses Swinburne’s MALDI-TOF mass
spectrometer to accurately identify strain-specific metabolic fingerprints.
These results are then fed into a database of different cell proteins allowing
the comparison of new strains with those previously identified. In an outbreak
situation this method could be used to quickly differentiate between unrelated
strains and those from the same source.

Faster
results

“Analysis is very quick,” says Professor Elena
Ivanova, microbiologist and one of Ahmed’s PhD supervisors. “You can get the
preparation stage down to one day and then get the results through the
MALDI-TOF in half an hour.” This greatly reduces the time and effort required
to identify the origin of a campylobacter jejuni contamination, meaning that
improved education, regulation or clean-up policies could be applied, therefore
also addressing some of the public health costs.

Developing a field-portable biosensor to aide in
tracing the source is the project’s ultimate goal. Fighting future outbreaks of
gastroenteritis will draw on these technologies, ensuring better health
outcomes for Victorians.